1. Distribution of light in the ocean
Sunlight zone
Biozone
Euphotic
Epipelagic
Disphotic
Mesopelagic
Bathypelagic
Aphotic
Abyssopelagic
Fig 13.9
Hatchet fish
2. Adaptations to the deep sea
•Bioluminescence
•Mating
•Feeding
Gulper eel
Female angler fish
Fig 15-14
Bioluminescence
A. Bioluminescence
a) What?
Definition: The emission of ecologically functional light by living organisms
Light is produced by a chemical reaction within the organism – no ‘input’ of energy
Note:
phosphorescence – emission of light with input of energy
fluorescence – input of energy to excite a molecule giving off light
b) Where?
• Marine bacteria
• Dinoflagellates
• All major phyla
c) How bioluminescence works
“optimizer”
Photon of light
enzyme
substrate
Core of the reaction
• has strong antioxidative properties
• detoxifies tissues by taking up oxygen free radicals
• usually brought into the system by diet or synthesis internally
d) Likely originated to detoxify oxygen derivatives
Bioluminescence in different
organisms
http://www.lifesci.ucsb.edu/~biolum/
chem/detail1.html
e) Examples of bioluminescent organisms & their
molecules:
1. Coelenterazine: most ‘popular’ of the luciferins (substrate);
known in cnidarians, molluscs, chaetognaths, fish.
•
•
•
•
•
Can act alone or with another enzyme
Often acts together with aequorin
Chemistry: Imidazolopyrazinone
Found in all tissues of the animal
Highest concentration in digestive gland, liver
hepatopancreas, organs with high levels of oxidative
reactions
2. Aequorin: a ‘luciferase’ (enzyme) that requires calcium
Aequorin is called a ‘photoprotein’ because it requires calcium to
work with a luciferin (such as coelenterazine)
O2
Apoaequorin
(enzyme)
Coelenterazine
(substrate)
Ca
2+
AequorinCoelenterazine
(excitable
intermediate)
Apoaequorin
photon
Colenteramide
And CO2
3. Bacterial luciferin: most often harnessed by other
animals and used for light emission (e.g. fish, squid)
Vibrio: a marine bacterium (free-living) that is an
endosymbiont in squid
Luminescence is dependent on cell density
(reduced riboflavin phosphate FMNH2 )
Aequoria victoria
f) When is bioluminescence used?
(1) lure
Angler Fish
(2) Burglar Alarm: startling predators of your predator
Cephalopod predation is facilitated by dinoflagellate luminescence
Pre-attack
‘Positioning’
‘Seizure’
Ghost shrimp
squid
(Fleisher and Case: Biol. Bull. 1995 189:263-271)
(3) Alarm/warning of other colonies:
e.g. Pyrosomes
Stops feeding and swimming current
http://divefilm.com/dive_films/indexC.html
More examples:
4) Krill – use bioluminescence for attracting mates
5) Bacterial endosymbiont in the squid Euprymna scolopes
E. scolopes burries in the sand during the day and forages at night.
Uses the bioluminescence produced by the Vibrio to counter-shade it
against the moonlight so that prey won’t see its shadow.
Hatchling squid pick up the bacteria and develop a special pouch
for them
B. Adaptations - Mating
Parasitic male
C. Adaptations - feeding
Chauliodus sloani
Large teeth
Hinged jaw
Chiasmodon niger
Vast stomach!
Fig 15-15
Chauliodus sloani
Gulper eel
Carnivorous tunicate
Atrial siphon
Oral siphon
(mouth)
Carnivorous sponge: Asbestopluma
From Barkley Sound
Amphipod
crustacean
Asbesopluma hypogea –
Carnivorous sponge from the Mediterranean (Marseille, France)